Conventionally, an organotin compound such as dibutyltin dilaurate, dibutyltin diacetate or dioctyltin dilaurate has been widely used as a curable composition for a synthetic resin. In recent years, such an organotin compound has been strongly demanded to be switched to a low-load compound in terms of both environment and health, and there has been proposed use of an amine compound and a carboxylic compound (see Patent Literature 1), use of a bismuth compound that is less problematic in terms of safety (see Patent Literature 2), use of a titanium alkoxide type catalyst, use of a guanidine compound as a silanol condensation catalyst (see Patent Literature 3), or the like, but none of them have yet replaced an organotin compound type curable composition currently used.
The above titanium alkoxide has been already known to have a function as a curable composition for a silicone type resin or a polyurethane resin. The titanium alkoxide provides titanium dioxide as a final decomposition product under a usual environment. Titanium dioxide is a highly safe compound to be added even to food additives and cosmetics. From such a reason, the titanium alkoxide is regarded as the most likely alternative of the curable composition for a synthetic resin.